Children with ADHD are twice as likely as to have faulty sections of genetic code, researchers at Cardiff University have said. Generally, people have two copies of most genes – one from mum and one from dad. But in children with ADHD, it appears that sometimes one copy is missing or there are too many copies, reports the Telegraph. This problem is called CNVs – copy number variants. CNVs play a role in other disorders, such as autism and schizophrenia.

“This is really exciting because it gives us the first direct genetic link to ADHD,” said professor of child and adolescent psychiatry Anita Thapar.

Sometimes ADHD is accused of being a label used for children who are just out of control due to bad parenting or poor diet. But, as Professor Anita said, "Now we can say with confidence that ADHD is a genetic disease and that the brains of children with this condition develop differently to those of other children."

Professor Anita hopes that the findings will change people’s attitudes to ADHD, in much the same way that attitudes to autism had moved on. She does point out that this discovery is unlikely to result in a genetic test for ADHD, because of all the other genetic and environmental factors involved.

The research included 366 children with ADHD and 1,000 children without.